In general, a driver seat, an occupant seat, and seats as other occupant seats, which are installed in front of and behind the interior of a vehicle, have various comfort devices for convenience of occupants.
The comfort devices have a sliding function of adjusting forward and rearward pushing/pulling of the seat, a reclining function of adjusting an inclination of a backrest, etc., according to body types of the occupants.
In addition, a vehicle, which is recently developed or has a predetermined reference or more, also includes a pumping device having a seat cushion lifting function of adjusting a height of a seat cushion 10 by receiving input from a handle lever 20 so as to be suitable for occupants, as illustrated in FIG. 1.
The pumping device is largely configured of a lever unit, a clutch unit, and a brake unit. The lever unit receives operating force of a user and transfers the operating force to the clutch unit. The clutch unit serves to transfer the input operating force (rotational force) of the user to a link means of the seat cushion 10. The brake unit serves to cut off power input in reverse so as to fix the link means an operation of which is completed.
The lever unit includes a lever bracket which converts vertical operating force of the handle lever 20 installed at one side of the seat cushion 10 into rotational force and transfers the rotational force to the clutch unit.
An output shaft, which finally transfers the operating force transferred from the clutch unit to the link means of the seat cushion 10, is fixed by the brake unit after the operation of the user is completed, thereby restricting the output shaft from rotating by power input in reverse.
As a specific example of the pumping device, there is a pumping device disclosed in Korean Patent No. 10-1117794.
The pumping device disclosed in the above patent includes a plurality of fitting pieces 8 which transfer rotational force of a clutch block to a clutch drum while rotating along with the clutch block, as illustrated in FIG. 2.
The plurality of fitting pieces 8 are provided with a plurality of adjacent rollers and has an arc shape as a whole. Accordingly, the plurality of fitting pieces 8 form a non-contact space S corresponding to a space between the rollers 8a and 8b located at both end portions of the plurality of fitting pieces 9 so as not to come into contact with the clutch block 4 in the non-contact space S. When rotational force acts on the clutch block 4, support force does act on a portion of an outer peripheral surface of the clutch block 4 facing the non-contact space S.
In the conventional pumping device for a vehicle seat having the above structure, a deviation is generated between loads acting on the respective rollers of the torque transfer portion 8, thereby causing deformation or damage on components.
Specifically, when the clutch block 4 rotates, for example, in the clockwise direction, reaction force acts on the clutch block 4 due to friction force between the clutch block 4 and the rollers.
In this case, the clutch block 4 tends to move toward the non-contact space S by a force F acting toward the non-contact space S from among force components of the reaction force.
By such a force F, stress concentration is generated on the roller 8b located at the right end portion of the torque transfer portion 8 from among the rollers thereof or on the rollers adjacent to the right end portion including the roller 8b. Such stress concentration causes the clutch drum 7, on which friction force acts by the roller, and other components, which are subject to force transferred from the clutch drum 7, to be deformed or damaged.